Field of the Invention
This invention relates to a sterilization container for use in sterilizing, storing and transporting and presenting instruments, in particular medical instruments.
Background of the Invention
Most, reusable medical instruments require sterilization before each use. Many methods are employed for sterilization, but the most prevalent methods include: steam autoclaving, vapor phase chemical sterilization and vapor phase chemical sterilization in combination with a plasma field. The chemical sterilants include hydrogen peroxide and ethylene oxide. One of the most versatile, quickest and most effective methods employs an initial period of vapor phase hydrogen peroxide followed by application of an electromagnetic field which drives the hydrogen peroxide vapor into the plasma state of matter. The plasma phase enhances the sterilization and when the electromagnetic field is released the plasma free radicals recombine to form water and oxygen.
Typically, instruments are placed into a container and then the container is placed into the sterilization device. Portals for the passage of sterilizing media must be provided. Also, the container is usually provided with a filter material which allows passage of the sterilizing media through the portals and container yet prevents the ingress of microorganisms. The portal and filter material may be combined as in the Nichols U.S. Pat. No. 4,704,254, issued Nov. 3, 1987 and incorporated herein by reference, or the container may be provided with a plurality of apertures and then be wrapped prior to each sterilization in a filter wrapping material such as SPUNGUARD brand CSR wrap available from Kimberly Clark Corporation which is a spunbonded/meltblown/spunbonded (SMS) laminate consisting of nonwoven outer layers of spun-bonded polyolefins and an interior barrier layer of melt-blown polyolefins.
Usually, holding devices of one form or another hold one or more individual instruments within the container. The holding device may comprise clips or other such arrangements, which may or may not be specially adapted to hold a particular medical instrument. One popular holding device simply comprises a plurality of upwardly extending flexible projections, sometimes called fingers, which prevent the instruments from moving about within the container and provide minimal contact with the instruments. Typically, these are provided on a mat which lies in the bottom of the container.
The ideal sterilization tray or container is compatible with all major sterilization methodologies, minimizes or eliminates condensation collection through thin, yet strong, walls, has a long life, is easy to operate and can be provided for a reasonable cost. Containers presently known suffer from shortcomings which limit their performance in one or more of these areas. For instance, many trays designed for steam autoclaves are formed of stainless steel which may interfere with formation of a plasma in some systems. Other trays made of polymers may not have sufficient heat resistance to withstand repeated steam sterilization cycles. Some tray materials interact with chemical sterilants, and may even decompose the sterilant. Other materials may absorb excessive amounts of chemical sterilants, thereby decreasing the sterilization effectiveness by decreasing the amount of sterilant available for sterilizing.
The present invention overcomes these and other limitations in the prior art and provides compatibility with hydrogen peroxide vapor, liquid or gas plasma, steam autoclaves, ethylene oxide and other chemical or heat based sterilizing methods. It is durable, inexpensive to produce, enhances drainage and limits condensate entrapment.
A sterilization container for sterilizing instruments according to the present invention, comprises a wall enclosing the container, means for holding a medical instrument within the container; and one or more openings into the container for admitting sterilizing gases. The wall is formed of a thermoplastic liquid crystal polymer whereby the wall resists chemical attack from hydrogen peroxide, ethylene oxide, and other chemical sterilants or their precursors, the wall does not unduly interfere with any electromagnetic fields, and the wall resists attack from elevated temperatures.
Preferably, the thermoplastic liquid crystal polymer comprises a wholly aromatic polyester. The liquid crystal polymer is preferably selected from the group consisting of: polybenzoate-naphthalate; polybenzoate-terephthalate-bisphenol-isophthalate; polybenzoate-terephthalate-ethylene glycol; and polynaphthalate-amino terephthalate. The liquid crystal polymer can be reinforced with a filler, such as glass, mineral fibers, or flouropolymers, in the form of powder, flakes or fibers.